DESCRIPTION: The most important function of a hearing aid (HA) is to amplify sound so as to compensate for loss of auditory sensitivity caused by hearing impairment. The ability of any HA to fulfill this function can be significantly compromised where amplified sound output from the HA receiver reaches the microphone and i re-amplified, causing the process to repeat in a regenerative closed loop system. The familiar result is oscillatory feedback (FB), manifest as audible distortion of sound quality and high pitched squealing, which renders the HA useless. At present there exists no practical solution to the problem of FM other than to reduce the gain of the HA, and thus to compromise its most important function. The primary objective of the proposed research is to implement a HA algorithm that can substantially reduce the problem of FM. We plan to develop and evaluate a high performance digital FM cancellation algorithm in a low power H circuit, and to transfer this algorithm and circuit to a HA manufacturer for implementation in commercially available hearing aids. We propose to conduct a three-year program of algorithm simulation and real-time implementation, digital circuit design and fabrication, prototype hearing aid construction, an laboratory field trial evaluations with normally hearing and hearing impaired subjects.